Dr. Kate is an OB/GYN at one of the largest teaching hospitals in New York City and she answers your medical questions here every two weeks. To ask her your own question, click here.

Dear Dr. Kate,

My mom’s hormones started changing when she was 38, and she actually got pregnant unexpectedly during this time. Is there a good way to practice birth control during pre-menopause? I understand that pills that have worked with your body for years warding off pregnancy can become ineffective at this time.

– Hot Flash

Dear H.F.,

The irony of perimenopause — the years of shifting hormones and irregular cycles that lead up to the total loss of your periods — is that you probably can’t get pregnant if you try… but that one occasional egg will lead to pregnancy if you don’t want it to.

Luckily, the same birth control methods that work for you in your 20s are still effective in your late 30s and early 40s. Hormonal methods, in fact, can lessen the bleeding irregularity and intense cramping that often come with perimenopause.

A warning, though: once you’re over 35, you may have contraindications to estrogen-containing methods (most pills, the patch, the ring) based on your medical history. If you’ve been a happy pill user, but smoke or have migraine headaches, your gyno will switch you to a progesterone-only method for safety reasons. And an IUD is always a good choice for most women, especially in perimenopause.

Dr. Kate is an OB/GYN at one of the largest teaching hospitals in New York City. She also lectures nationally on women‚Äôs health issues and conducts research on reproductive health. Check out more of her advice and ask her a question at Gynotalk.com.